Development of a novel in situ phenotyping methodology to measure nitrification in the rhizosphere.

Nitrogen (N)-fertilisers, commonly applied as ammonium (NH4+) support half of the world food production but globally up to 50% are lost to the environment through leaching of the soluble form nitrate (NO3-) and gaseous emissions of greenhouse gas nitrous oxide (N2O). Nitrification is the oxidation process of NH4+ into soluble NO3- by soil bacteria. Reducing nitrification rates in soils may lower N-fertilisers losses and lead to higher agronomic N use efficiency (NUE). Certain plants can control nitrification rate releasing inhibitors from their roots in the rhizosphere, called biological nitrification inhibitors (BNI). It is crucial to identify BNI activity in elite varieties of staple crops or in historic landraces from which the trait could be bred into commercial varieties. In this proposal, we plan to develop an in-situ methodology for spatially resolved detection of the nitrification in the rhizosphere of wheat genotypes grown in soil with the ambition that these can be applied in the field. In-situ methods, acting as an in-situ reporter for BNI, may provide more accurate information compared to conventional destructive methods. Two methods based on Diffusive Gradients in Thin (DGT) film imaging technique for 2D mapping of NH4+ and NO3- in the rhizosphere will be developed and applied to phenotype BNI activity in a collection of wheat lines and relevant recombinant populations.